SETI: Science, or Religion?
One does not gauge scientific credibility by short-term success in validating a particular hypothesis -- after all, it took more than half a century to produce compelling evidence to support some of Einstein's theories. What marks a field of study as scientific (or not) is the testability (or, more properly, falsifiability) of its underlying hypotheses, and the level of rigor brought to the related experimental design. When we demand the highest possible standard of proof before accepting proffered evidence, we are applying the scientific method -- hence, are practicing science. This is, I believe, what differentiates SETI science from UFO pseudoscience.
The accusation that SETI is based upon a non-falsifiable hypothesis is valid only if one believes that the objective of SETI research is to prove the existence of extraterrestrial intelligence. Any experiment which adopts that goal is poorly designed, because it becomes open-ended. Better to establish a null hypothesis, which it takes only
one counter-example to disprove. For example: I would hypothesize that there are no extraterrestrial civilizations that emit artificial electromagnetic radiation which can be detected on Earth, at our current level of technology. Presently (and for more than 40 years), our research supports this hypothesis. But a single confirmed detection would falsify the null hypothesis, thus lending credence to an alternative hypothesis (that we are not alone).